More than 21% of adult Americans (46 million) have some form of diagnosed arthritis, and the number is anticipated to rise to 67 million by 2030 (Hootman and Helmick, 2006). The most common type of arthritis, osteoarthritis (OA), affected more than 27 million Americans (Lawrence et al., 2008). Nearly one-half of all adults and two-thirds of those who are obese can now be expected to develop symptomatic knee OA at some point in their lives (Murphy et al., 2008). Knee OA is a major contributor to functional impairment and reduced independence in older adults (Peat et al., 2001).
There is a growing recognition of the role of local neuromechanical factors in influencing physical function and knee OA disease progression. One such factor is varus-valgus laxity and dynamic instability. However, few exercise treatment strategies to target this particular biomechanical and neuromuscular impairment exist.
Although it is well recognized that knee OA is associated with excessive knee adduction moment (KAM) in the frontal plane, there has been a lack of convenient and effective ways of training people with knee OA in better dealing with the frontal plane knee adduction moment loading.
In general, one or more components of lower-limb joint moments may need to be better controlled through feedback training for the purposes of post-injury rehabilitation and injury prevention. There is a general need for real-time feedback training of selected joint moment(s).
The multi-axis rehabilitation system described here addresses such a need and provides us a useful tool to better control a certain joint moment through real-time biofeedback of the targeted joint moment(s).